Isaacs U.S. Pat. No. 1,152,539 and Del Mas U.S. Pat. No. 2,760,303 are early inventions disclosing toys mounted on springs to impart rocking, bobbing or wobbling motion to a toy or amusement device.
Cohn U.S. Pat. No. 2,504,652 discloses a toy incorporating a power driven mechanism for creating a back-and-forth action to the toy.
Norton U.S. Pat. No. 5,169,354 provides an off-center weight to the driven shaft which creates a wobble or rocking motion to the device as do also the patents of Lin U.S. Pat. No. 5,360,366, Hughes U.S. Pat. No. 4,536,167 and Ku U.S. Pat. No. 5,720,644. In all of these developments, those that use a motor mechanism, have the drive shaft rotating to cause the offset weight to rotate.